Wireless signal applications continue to increase in the commercial and military industries. As such, the number of radio transceivers are increasing and transmitting at higher output power. Some higher output transceivers must operate in the same radio band and use antennas that are in close proximity to other transceivers on a platform. These situations, where multiple radios are in close proximity to each other, may be referred to as co-located (cosite) radios.
Cosite transceivers can create an increased level of system self-interference. Most transceiver systems designed to solve cosite interference, rely on simple receiver frequency or power pre-selection. However, they sometimes do not adequately address cosite self-interference issues. Additionally, some of these transceivers may use low power band pass filtering before the transmitter power amplifier to reduce the undesired spectral content of the exciter. Yet, these methods are proving to be inadequate for current radio networks and other wireless networks.
Radio networks that only use two cosite transceivers typically employ a receiver pre-selector to remove the neighboring transmitter signal from the receiver input. In some cases there is a low-power filter in the nearby transmitter to reduce the sideband interference. In essence, both filters are used to prevent the one transceiver's transmit signal from interfering with the other transceiver's ability to receive a desired remote signal. While this method may be desirable in some situations, it is often only effective under ideal or constant power conditions of the signal received at the receiver. However, power levels of the received signal of interest are not always at a constant power level.